Detection of Majorana non-locality in hybrid dot-nanowire systems I: theory

The spatial non-locality nature of Majorana bound states (MBS) is the key ingredient for their topological protection. While several tunneling experiments have reported Majorana signatures in the form of a zero-bias conductance peak, a demonstration of non-local Majoranas as opposed to local Andreev levels coalescing near zero energy is still lacking. Here we demonstrate that a local transport measurement can be used to quantify the degree of Majorana non-locality associated to a zero-bias peak. This seemingly contradicting result can be achieved by measuring the sensitivity of the zero-energy state to a local perturbation created by a gate-tunable quantum dot located at the end of a nanowire, which simultaneously acts as a tunnel spectroscopic probe. The degree of sensitivity is then connected to the Majorana wavefunction overlap using theoretical tools [1]. Using this approach, we observed zero-bias peaks from low to high degree of wavefunction non-locality [2]. The first part of this talk (I) will focus on theory aspects while the second part (II) will present the experimental data.
[1] E. Prada, R. Aguado and P. San-Jose, Phys. Rev. B 96, 085418 (2017)
[2] M. T. Deng, S. Vaitiekenas, E. Prada, P. San-Jose, J. Nygard,1 P. Krogstrup, R. Aguado and C. M. Marcus, in preparation.